The overall goal is to perform experiments which will: (1) provide insight into factors regulating the synthesis and degradation of alveolar macrophage (PAM) proteins, (2) study factors modulating the degradation by PAM of proteins normally present in the alveolar lining layer and (3) examine the role of lysosomes of the PAM in the process of protein degradation. We shall study the influence of substrates (glucose, amino acids), hormones (insulin, corticosteroids and glucagon), different oxygen tensions and starvation on protein synthesis, the degradation of slow and fast turning-over PAM proteins and the degradation of proteins exogenous to the PAM (the apoprotein of pulmonary surfactant and serum albumin). We anticipate that these experiments will (1) generate information useful to our understanding PAM function, (2) provide a basis for comparing protein metabolism in the PAM to other cell systems and (3) will provide information on factors regulating the degradation of phagocytosed proteins.